package org.jboss.windup.util.xml;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang3.StringUtils;

/**
 * Util methods to work with XML DOCTYPE's.
 */
public class DoctypeUtils {

    public static String extractVersion(String publicId, String systemId) {
        Pattern pattern = Pattern.compile("[0-9][0-9a-zA-Z.-]+");

        if (StringUtils.isNotBlank(publicId)) {
            Matcher matcher = pattern.matcher(publicId);
            if (matcher.find()) {
                return matcher.group();
            }
        }

        if (StringUtils.isNotBlank(systemId)) {
            Matcher matcher = pattern.matcher(systemId);
            if (matcher.find()) {
                String match = matcher.group();

                //for system ID, make sure to remove the ".dtd" that could come in.
                return StringUtils.removeEnd(match, ".dtd");
            }
        }

        return null;
    }
}
